The invention is more particularly aimed at a rim that is not airtight, originally designed to accept a tire intended to be mounted with an inner tube, and that is to be rendered airtight so that it can accept a tire of the “tubeless” type (fitted without an inner tube). However, the invention is also applicable to an airtight rim onto which there is a desire to fit, for example, a tire that has a lower region that is not very or not at all airtight.
Although not restricted to this type of application, the invention will be described more specifically with reference to a rim that is not airtight for a spoked bicycle wheel.
Bicycle wheels usually consist of a rim connected to a hub by spokes. These spokes are fixed to the rim by tightening nuts, these nuts being accessible from the radially exterior surface of the rim so that the spoke tension can be adjusted. The rim therefore has orifices distributed about its periphery to secure the tops of the spokes which, once in place, do not seal the said orifices.
When the wheel is intended to be associated with a tire and an inner tube, the lack of airtightness of the radially exterior surface of the rim does not present any problem when riding in a non-degraded mode. The presence of the tops of the spokes or of the tightening nuts does, however, entail the presence of a tape in the bottom of the rim in order to protect the inner tube from friction; if this tape were not present, the tops of the spokes or the nuts could tear the inner tube.
It is also known practice to produce mounted assemblies of the tubeless type for bicycles. Patent application EP 0 893 280 has already described a rim of the tubeless type. This type of rim allows set-ups of the tubeless type which have various advantages: first, they make it possible to dispense with the need for an inner tube, leading to cost savings, weight savings and ease of assembly. Furthermore, the absence of an inner tube allows the mounted assembly to be made less sensitive to tires that go flat as a result of nipping or puncturing.
By contrast, the costs of manufacture of such rims are far higher, which means that their circulation is not widespread.
Intermediate solutions have been developed to enable mounted assemblies of the tubeless type to be produced at a lower cost. Such solutions have, for example, been described in documents U.S. Pat. No. 4,108,232 and US 2005/0189813. Those documents describe sealing devices designed to be installed by hand and which consist in an annular band (or “flap”) which is housed in the bottom of a rim and thus seals the said rim. Such devices are inexpensive and can therefore allow a bike mounted assembly of the tubeless type to be produced using rims of the “standard tube” type, which are therefore more cost-effective than the tubeless rims mentioned above.
By contrast, it has been found that the various existing devices are tricky to fit notably because of the complex centering required which could lead to imperfect airtightness. Even in the hands of an experienced user, these solutions designed for converting a standard tubed rim into a tubeless rim remain very tricky to perform and are therefore used only very infrequently. Furthermore, the properties of these annular bands and particularly their rigidity lead, even if the user has managed to fit them, to microleaks if the surface finish of the rims has even the slightest relief such as welds or other roughnesses.
According to the invention, “axial” means a direction parallel to the axis of rotation of the rim, and “radial” means a direction intersecting the axis of rotation of the rim and perpendicular to that axis. The axis of rotation of the rim is the axis about which the rim turns in normal use. The circumferential median plane is a plane perpendicular to the axis of rotation of the rim and which divides the rim into two halves. A plane that is said to be radial or meridian is a plane that contains the axis of rotation of the rim.